Methods of analyzing crude oil

ABSTRACT

The invention generally relates to methods of analyzing crude oil. In certain embodiments, methods of the invention involve obtaining a crude oil sample, and subjecting the crude oil sample to mass spectrometry analysis. In certain embodiments, the method is performed without any sample pre-purification steps.

RELATED APPLICATION

The present application claims the benefit of and priority to U.S.provisional patent application Ser. No. 61/759,097, filed Jan. 31, 2013,the content of which is incorporated by reference herein in itsentirety.

GOVERNMENT SUPPORT

This invention was made with government support under DE-FG02-06ER15807awarded by Department of Energy. The government has certain rights inthe invention.

FIELD OF THE INVENTION

The invention generally relates to methods of analyzing crude oil.

BACKGROUND

Pipelines are generally the most economical way to transport largequantities of crude oil, refined oil products or natural gas over land.Steel pipes are commonly used, which can be subject to both internal andexternal corrosion. Corrosion protection is a critical process to ensurecontinuous pipeline operation.

Corrosion of oil transmission pipelines can result in leakage and largescale oil spills that are destructive of the ecosystem and pollutedrinking water supplies (Sastri, Corrosion Inhibitors: Principles andapplications, J. Wiley & Sons, New York, 2001, Ch 1, pp 5-30; Sacher, etal., J. Chromatogr, A, 1997, 764, 85-93; Zhao et al. Materials andCorrosion, 2004, 55, 684-688; Son, NACE International CorrosionConference Series, 2007, 07618; Valentine, et al., Science, 2010, 330208-211; Kujawinski, et al., Science & Technology, 2011, 45, 1298-1306;Thibodeaux, et al., Environmental Engineering Science, 2011, 28, 87-93;Bjorndal, et al., Science, 2011, 331, 537-538; and Atlas et al.,Environmental Science & Technology, 2011, 45, 6709-6715). Corrosion istypically inhibited through addition to crude petroleum of oil-solubleheterocyclic compounds, such as quaternary ammonium salts and ionicliquids (Quraishi et al., Am. Oil Chem. Soc., 2000, 77, 1107-1111,Treybig et al., U.S. Pat. No. 4,957,640; Derek et al., U.S. Pat. No.4,235,838; and Young et al., U.S. Pat. No. 6,645,399). Successfulinhibition depends on the amount of inhibitor, and so measurement ofinhibitor levels in crude oil is of great interest, especially inlong-distance transfer pipelines (Nyborg et al., NACE-International,Corrosion Conference Series, 2012, 6, 4582-4590; Kvarekvål,NACE-International Corrosion, Conference Series, 2012, 6, 4329-4352; andDugstad et al., NACE-International, Corrosion Conference Series, 2012,5, 3573-3586).

Currently, no standard method exists for direct in-field monitoring ofresidual levels of corrosion inhibitors. Gas chromatography or highperformance liquid chromatography combined with mass spectrometry (GC-MSor HPLC-MS) is the most widely adopted method for ex-situ quantificationof residual corrosion inhibitors and other oil constituents. (Sacher etal., J. Chromatogr, A, 1997, 764, 85-93; Son, NACE InternationalCorrosion Conference Series, 2007, 07618; Huhn et al., J. Anal. Chem.,1995, 351, 563-566; Gough et al., NACE-International, Corrosion, 98paper, No 33; Schwartz et al., Anal. Chem., 1990, 62, 1809-1818; Chianget al., Chemistry of Materials, 1992, 4, 245-247; Hsu, Anal. Chem.,1993, 65, 767-771; March, J. Mass Spectrom., 1997, 32, 351-369; and Heet al., Energy Fuels., 2011, 25, 4770-4775). Although highly sensitiveand specific, these methods are time consuming, requiring numeroussample purification and preparation steps prior to analysis. Due to thesample work-up required prior to analysis, samples need to be taken tothe laboratory for analysis.

SUMMARY

The invention provides methods for analyzing a crude oil sample by massspectrometry in an unmodified form from which it was obtained.Accordingly, methods of the invention may be performed without anysample pre-purification steps. Aspects of the invention are accomplishedusing wetted porous material as a substrate for the mass spectrometryanalysis. An unmodified crude oil sample, such as that extracted from anoil transmission pipeline, is directly introduced to a porous substrate.Solvent and voltage is applied to the substrate to generate ions of ananalyte in the sample. Those ions are directed into and analyzed by amass spectrometer. In that manner, methods of the invention providerapid and efficient in-field mass spectrometry techniques for theanalysis of crude oil, such as monitoring corrosion inhibitors in thecrude oil in transmission pipelines.

In certain aspects, the invention provides methods for analyzing a crudeoil sample that involve obtaining a crude oil sample, and subjecting thecrude oil sample to mass spectrometry analysis. The methods of theinvention may be performed without any sample pre-purification steps,i.e., the sample is taken directly from its source and is directlyanalyzed by mass spectrometry without any additional modification to thesample. In certain embodiments, the mass spectrometry analysis isperformed in an ambient environment.

In certain embodiments, the mass spectrometry analysis involvesintroducing the crude oil sample to a porous substrate, applying solvent(e.g., a mixture of methanol and acetonitrile) and voltage to thesubstrate to generate ions of an analyte in the crude oil sample, andanalyzing the ions using a mass spectrometer. Numerous different typesof porous substrates may be used with methods of the invention, and suchsubstrates are described in greater detail below. An exemplary poroussubstrate is paper, such as filter paper. The mass spectrometer may be abench-top mass spectrometer or a miniature mass spectrometer. In certainembodiments, the mass spectrometer or miniature mass spectrometer iscoupled to a discontinuous atmospheric pressure interface.

Methods of the invention may be used to analyze numerous different typesof analytes in crude oil. In certain embodiments, the analyte in thecrude oil is a corrosion inhibitor. The corrosion inhibitor may includeat least one alkyl ammonium salt, such as tetradodecylammonium bromide,benzylhexadecyldimethylammonium chloride, or a combination thereof.

Other aspects of the invention provide methods for quantifying acorrosion inhibitor in crude oil. The methods involve obtaining a crudeoil sample including a corrosion inhibitor, subjecting the crude oilsample to mass spectrometry analysis, and quantifying the corrosioninhibitor in the crude oil sample based on results of the massspectrometry analysis, in which the method is performed without anysample pre-purification steps.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic showing paper spray mass spectrometry for in-situanalysis of corrosion inhibitors in oil using a miniature massspectrometer.

FIG. 2 is a calibration curve for the quantitative analysis of ammoniumsalts in oil matrix using a commercial ion trap mass spectrometer

FIGS. 3A-B are mass spectra showing positive ion mode paper spray massspectra for quaternary ammonium corrosion inhibitor model compoundsanalyzed using a bench-top ion trap instrument. Absolute amounts ofanalytes spotted onto filter paper and ionized in air by application ofan electric potential were 100 pg of each compound in 1 uL of oil, viz.100 ppb. FIG. 3A shows tetraoctyl ammonium bromide at m/z 466.6. FIG. 3Bshows tetrabutylammonium hexafluorophosphate at m/z 242. Insert (i)shows the isotopic distribution of the analyte ion and inserts (ii)-(vi)show MS/MS CID data for selected ions, again using 100 pg of analyte in1 μL of oil.

FIG. 4A is a positive ion mode paper spray mass spectrum for the modelcompounds in mixtures in vacuum pump oil analyzed using a benchtopinstrument; tetrabutylammonium bromide gives the intact cation at m/z242, hexadecytrimethylammonium bromide at m/z 284,benzylhexadecyldimethylammonium chloride at m/z 360, tetraoctylammoniumbromide at m/z 466.6 and tetradodecylammonium bromide at m/z 691. FIG.4B is a typical positive ion paper spray mass spectra foralkyldimethylbenzyl ammonium chloride [C₆H₅CH₂N (CH₃)₂R]Cl in which R ispredominantly n-C₁₂H₂₅ but also contains C₁₄ and C₁₆ homologs) standardanalyzed using a benchtop ion trap mass spectrometer. Inserts i), ii)and iii) are the CID mass spectra for the m/z 304 (C₁₂), m/z 332(C_(m)), m/z 360 (C₁₆) respectively.

FIGS. 5A-D are positive ion paper spray mass spectra of quaternaryammonium corrosion inhibitor model compounds analyzed in oil (1 μL)using a handheld miniature instrument. Absolute amounts of analytesspotted on paper were 100 pg of each compound. FIG. 5A is tetraoctylammonium bromide, FIG. 5B is benzylhexadecyldimethyl ammonium chloridein vacuum pump oil artificial mixture, and FIGS. 5C-D are the CID massspectra of the samples respectively.

FIG. 6A is a positive ion paper spray mass spectrum for the modelcompounds artificial mixtures in vacuum pump oil analyzed using ahandheld miniature instrument absolute amounts of analytes was spottedon paper were 1 ng/μL (absolute concentration); tetrabutylammoniumbromide at m/z 242, hexadecytrimethylammonium bromide at m/z 284,benzylhexadecyldimethylammonium chloride at m/z 360, tetraoctylammoniumbromide at m/z 466.6 and tetradodecylammonium bromide at m/z 691. FIG.6B is a typical positive ion paper spray mass spectra foralkyldimethylbenzyl ammonium chloride [C₆H₅CH₂N (CH₃)₂R]Cl where R ispredominantly n-C₁₂H₂₅ but also contains m/z 332 (C₁₄) and m/z 360 (C₁₆)homologs) standard analyzed using a benchtop ion trap mass spectrometer,and FIGS. 6C-D show the CID MS/MS data for the of m/z 304 (C₁₂) and m/z332 (C₁₄) mixture components, respectively.

FIG. 7 is a positive paper spray-MS mass spectrum ofhexadecyltrimethylammonium bromide. Insert (i) shows the isotopicdistribution of the analyte, tandem mass spectrometry (MS/MS) of thehexadecyltrimethylammonium cation at m/z 284.0 did not return goodsignal since the expected major fragment is below the low mass cut offthe instrument.

FIG. 8 is a positive paper spray-MS mass spectrum oftetradodecylammonium bromide. Insert (i) shows the isotopic distributionof the analyte, (ii)-(iii) Tandem mass spectrometry (MS/MS) of thetetraoctylammonioum cation at m/z 691.0 gives a major fragment ion atm/z 522.0 with a alkene loss of 112.0 and a minor fragment ion at 520.0with a alkane loss of 114, which confirm the structure. Again (iii)MS/MS/MS of the major fragment ion at m/z 522.0 (major) fragmentsfurther to give an ion at m/z 354.5 and ion at m/z 352.5 with a neutralloss of −[112] and −[114] respectively further confirming the identityof the compound.

FIG. 9 is a positive paper spray-MS mass spectrum of tetrahexylammoniumbromide. Insert (i) shows the isotopic distribution of the analyte ion,(ii)-(iii) Tandem mass spectrometry (MS/MS) of the tetrahexylammoniumcation at m/z 354.7 gives a major fragment ion at m/z 270.0 with a lossof alkene −[84] and a minor fragment ion at 268.5 with a loss of alkane−[86] that confirms the structure. Again (iii) MS/MS/MS of the majorfragment ion at m/z 270.0 fragments further to give an ion at m/z 186.0(major) and ion at m/z 184.0 (minor) with a neutral loss of −[84] and−[86] respectively further confirming the identity of the compound.

FIG. 10 is a positive paper spray-MS mass spectrum ofbenylhexadecyldimethylammonium chloride. Insert (i) shows the Isotopicdistribution of the analyte ion, (ii) Tandem mass spectrometry (MS/MS)of the benylhexadecyldimethylammonium cation at m/z 360 gives a majorfragment ion at m/z 268 with a loss of alkene −[92] that confirms thestructure.

FIG. 11 is a positive ion mode paper spray mass spectrum for artificialmixtures of model compounds analyzed using a benchtop instrument.Tetrabutylammonium bromide was observed at m/z 242.0,hexadecytrimethylammonium bromide at m/z 284.0,benzylhexadecyldimethylammonium chloride at m/z 360.0,tetraoctylammonium bromide at m/z 466.6 and tetradodecylammonium bromideat m/z 691.0.

FIG. 12 is a typical positive ion paper spray mass spectra for a mixtureof alkyl dimethylbenzyl ammonium chloride salts [C₆H₅CH₂N(CH₃)₂R]Clwhere R is predominantly n-C₁₂H₂₅ (also contains small amounts of m/z332 (C₁₄) and m/z 360 (C₁₆) homologs) standard analyzed using a benchtopion trap mass spectrometer. The trace levels of C₁₆ homolog, aremanifest in the relative abundances compared with other components inthe mixture.

FIG. 13 shows ion chronograms for the for alkyl dimethylbenzyl ammoniumchloride [C₆H₅CH₂N (CH₃)₂R]Cl where R is predominantly n-C₁₂H₂₅; datafor the homologs C₁₄ (m/z) 332, C₁₂ (m/z) 304, and C₁₆ (m/z) 360 areshown.

FIG. 14A shows a schematic of a sample solution being fed to a piece ofpaper for electrospray ionization. FIG. 14B shows a schematic of asample, such as crude oil, pre-spotted onto the paper and a droplet ofsolvent being subsequently supplied to the paper for electrosprayionization.

FIG. 15 shows a schematic showing a discontinuous atmospheric pressureinterface coupled in a miniature mass spectrometer with rectilinear iontrap.

DETAILED DESCRIPTION

The invention generally relates to methods for analyzing crude oil.Crude oil refers to a naturally occurring, unrefined petroleum productcomposed of hydrocarbon deposits. Crude oil is refined to producepetroleum products such as gasoline, diesel and various forms ofpetrochemicals. Methods of the invention can analyze any analyte withinthe crude oil. An analyte refers to any substance or chemical in thecrude oil that can be identified and/or measured. The analyte may be anaturally occurring substance or chemical in the crude oil (e.g.,paraffinsm naphthenes, aromatics, or asphaltics). Alternatively, theanalyte may be a non-naturally occurring substance or chemical that isfound in the crude oil. Exemplary non-naturally occurring substances orchemicals that are found in crude oil include corrosion inhibitors,emulsion breakers, hydrogen sulfide controllers, paraffin controladditives, scale inhibitors, hydrate inhibitors (e.g., ethylene glycoland methanol), dehydrators (e.g., triethylene glycol), bactericides(e.g., quaternary amine salt, amine acetate, and gluteraldehyde), anddefoamers (e.g., silicones and polyglycol esters).

A corrosion inhibitor refers to a chemical compound that, when added toa liquid or gas, decreases the corrosion rate of a material, typically ametal or an alloy. Corrosion inhibitors are further described, forexample in Son (“Developments In The Laboratory Evaluation Of CorrosionInhibitors: A Review”, NACE Corrosion 2007 Conference and Expo, Papernumber 07618); Son (Corrosion, 2004, NACE International Conference,paper number 04373); Buck et al. (U.S. Pat. No. 5,152,177); Quraishi etal. (Am. Oil Chem. Soc., 2000, 77, 1107-1111); Treybig et al. (U.S. Pat.No. 4,957,640); Derek et al. (U.S. Pat. No. 4,235,838); and Young et al.(U.S. Pat. No. 6,645,399), the content of each of which is incorporatedby reference herein in its entirety. In certain embodiments, thecorrosion inhibitor includes alkyl ammonium salts, such astetradodecylammonium bromide and/or benzylhexadecyldimethylammoniumchloride. Commercially available corrosion inhibitors are sold byWeatherford, such as those described in Table 1 below.

TABLE 1 Alpha 1018 - 75 to 80% active alkyl pyridine benzyl quaternaryammonium chloride used to formulate corrosion preventives forapplications in oil well drilling, completion, production, and waterflood systems. Highly cationic amine compound that is normally dilutedor formulated with other additives, such as nonionic surfactants andalcohols, for application purposes. Alpha 1505 - 48 to 52% active benzylquaternary ammonium chloride used to formulate corrosion preventives forapplications in oil well drilling, completion, production, and waterflood systems. Highly cationic amine compound that is normally dilutedor formulated with other additives for application purposes. Alpha3013 - 85 to 90% active blend of alkyl benzyl quaternary ammoniumchloride, aliphatic amines, and anionic surfactant to formulatecorrosion inhibitors for use in oil and gas pipelines, producing wells,and water flooding systems. Also provides corrosion protection for oilwell acidizing, high temperature gas wells, and refinery applications.Highly cationic amine compound that is normally diluted (25% by volumewith water) or formulated with other additives for application purposes.Alpha 3058 - 40% active blend of alkyl pyridine benzyl quaternaryammonium chloride, nonionic surfactant, and acetylenic alcohols toformulate corrosion inhibitors for use in oil and gas pipelines,producing wells, and water flood systems. Effective corrosion inhibitorfor oil well acidizing additives, high temperature gas wells, orrefinery applications. Highly cationic amine compound that is normallydiluted or formulated with other additives for application purposes.Alpha 3149 - Blend of alkyl pyridine benzyl quaternary ammoniumchloride, nonionic and anionic surfactants to formulate corrosioninhibitors for use in oil and gas producing wells, gathering systems,and water flooding systems. Effective in high temperature gas wells andrefinery applications. Can be diluted with alcohols, glycols, orwater-alcohol solutions for application purposes. Alpha 3412 - 75 to 80%active blend of alkyl pyridine benzyl quaternary ammonium chloride,nonionic and anionic surfactants used to formulate corrosion inhibitorsfor use in oil and gas producing wells, gathering systems, and waterflooding systems. Can be diluted with alcohols, glycols, orwater-alcohol solutions for application purposes. Alpha 3435 - 53 to 57%active blend of alkyl pyridine benzyl quaternary ammonium chloride saltand nonionic surfactant designed as a corrosion inhibitor for use in oilwell drilling, completion, production, and water flooding systems.Cationic amine compound that can be used as a surfactant for well cleanout and stimulation operations. Alpha 3444 - 77 to 83% active blend ofalkyl pyridine benzyl quaternary ammonium chloride, nonionic and anionicsurfactants used to formulate corrosion inhibitors for use in oil andgas producing wells, gathering systems, and water flooding systems.Highly cationic amine compound that can be diluted with alcohols,glycols, or water/alcohol blends. Alpha 7368 - 23 to 28% active amine,quaternary ammonium chloride, and sulfite blend used as corrosionpreventives in oil well drilling completion, producing, and waterflooding systems. Recommended for use in saltwater packer fluid anddrilling fluids. Concentration range of 500 to 2000 ppm when used as ahydrostatic corrosion inhibitor. Alpha 7369 - 23 to 28% active amine,quaternary ammonium chloride, and sulfite blend used as corrosionpreventives in oil well drilling completion, producing, and waterflooding systems. Recommended for use in saltwater packer fluid anddrilling fluids. Concentration range of 500 to 2000 ppm when used as ahydrostatic corrosion inhibitor. Alpha 2095 - 68 to 72% active cocoaminediquaternary ammonium chloride used to formulate corrosion preventivesfor applications in oil well drilling, completion, production, and waterflood systems. Highly cationic amine compound that is normally diluted(50% by weight with water) or formulated with other additives forapplication purposes. Alpha 2129 - 83 to 87% active cocomine quaternaryammonium chloride in an aqueous solution that is used as a surfactant toimprove water injectivity in water floods. Can be used as a corrosionpreventative in water floods or in produced water handling systems.CE-152 - 78 to 82% active alkyl dimethyl benzyl quaternary ammoniumchloride used as a corrosion preventative for water systems or downholeproducing oil wells. The alkyl groups are C-12, C-14, and C-16.Effective against sulfide corrosion. Often blended with demulsifiers to“wet” sulfides and other solids that cause emulsion problems. Alpha 1153(CE-123)/(CI-811) - 98 to 100% active imidazoline derived from monobasicfatty acids to formulate corrosion inhibitors for use in drilling,production, transporting, and refining of crude oil. Can be formulatedwith inorganic and organic acids to form liquid, water-soluble salts foruse as corrosion preventives, emulsifiers, wetting agents, or scalepreventives. Used in concentrated form or diluted for applicationpurposes. Alpha 1215 - 98 to 100% active polyamide derived from fattyacids used to formulate thermally stable corrosion preventives forapplications in drilling, production, transporting, and refining ofcrude oil. Can be formulated with inorganic and organic acids to formwater-soluble salts for use as corrosion preventives, emulsifiers,wetting agents, or scale preventives. Highly cationic amine that can beused in concentrated form or diluted for application purposes. Alpha1378 - 78 to 82% active modified amido polyamine derived from oleylfatty acids to formulate corrosion inhibitors for use in drilling,production, transporting, and refining of crude oil. Can be formulatedwith inorganic and organic acids to form liquid, water-soluble salts foruse as corrosion preventives, emulsifiers, wetting agents, or scalepreventives. Alpha 1386 - 98 to 100% active alkylamidomine derived frommonobasic acids to formulate corrosion inhibitors for use in drilling,production, transporting, and refining of crude oil. Can be formulatedwith inorganic and organic acids to form liquid, water-soluble salts foruse as corrosion preventives, emulsifiers, wetting agents, or scalepreventives. Alpha 3198 - 98 to 100% active complex polyamine derivedfrom fatty acids used to formulate thermally stable corrosionpreventives for applications in drilling, production, transporting, andrefining of crude oil. Can be formulated with inorganic and organicacids to form liquid, water- soluble salts for use as corrosionpreventives, emulsifiers, wetting agents, or scale preventives. Highlycationic amine that can be used in concentrated form or diluted forapplication purposes. CI-821 (CE-72) - 98 to 100% active amidoimidazoline derived from monobasic acids to formulate corrosioninhibitors for use in drilling, production, transporting, and refiningof crude oil. Can be formulated with inorganic and organic acids to formliquid, water-soluble salts for use as corrosion preventives,emulsifiers, wetting agents, or scale preventives. Alpha 2290 - 98 to100% active alkyl phosphate ester, acid form, designed as a corrosioninhibitor for use in water injection systems. Anodic inhibitor thatcontrols general and pitting corrosion for oxygen, hydrogen sulfide, andcarbon dioxide. Should be maintained at concentrations of 500-2000 ppmin most systems. Alpha 2296 - 52 to 58% active potassium salt of aglycol phosphate ester designed as a corrosion inhibitor for use inwater injection systems. Anodic inhibitor that controls general andpitting corrosion for oxygen, hydrogen sulfide, and carbon dioxide.Should be maintained at concentrations of 500-2000 ppm in most systems.Alpha 3385 - 61 to 65% active amine salt of poly-phosphate ester thatfunctions as a combination oil-soluble scale and corrosion inhibitoradditive. Also functions as a refinery antifoulant and corrosioninhibitor for product pipelines. Can be used in concentrated form ordiluted with hydrocarbon solvents or oil for application purposes. Alpha3220 - 70 to 75% active soluble organic-boron amine solution used toprepare corrosion inhibitors for oxygen, carbon dioxide, hydrogensulfide, organic and mineral acids, and dissolved salts for applicationsin oil, gas, or water well producing systems and in water injectionsystems. Can be diluted with water, water-alcohol, or water-glycolsolutions for application purposes. CI-810 (CE-86) - 100% active tallowdiamine ethoxylate (10 moles of EO) used as an extremely versatilecorrosion inhibitor base with high detergent properties. Used in bothwater-soluble and oil soluble formulations and is a strong film formingagent. Alpha 3356 - 70 to 75% active complex fatty acid-amine salt usedto formulate thermally stable corrosion preventives for applications indrilling, production, transporting, and refining of crude oil. Used as acorrosion prevention additive in oil systems, water floods, and waterdisposal systems. Can be used in concentrated form or diluted withhydrocarbon solvents, isopropanol, or water-isopropanol solutions forapplication purposes. Alpha 3370 - 88 to 90% active polyacid, organicacid-polyamide salt with quaternary ammonium chloride used as acorrosion inhibitor in drilling, producing, transporting, and refiningof crude oil. Functions as corrosion preventive and anti-foulant in oilsystems, water floods, and water disposal systems. Can be used inconcentrated form or diluted (20-50% by volume) with hydrocarbonsolvents for application purposes. Alpha 7370 is a 30% dilution of Alpha3370 to yield a 25 to 29% active product in a hydrocarbon solvent. Alpha7420 is a 22% dilution of Alpha 3370 to yield a 18 to 22% active productin a hydrocarbon solvent. Alpha 3456 - 12 to 16% active amine salt ofpolyphosphonic acid designed as an oil-soluble scale inhibitor for watersystems. Contains cationic amines to create a combination scale andcorrosion prevention product that is thermally stable in excess of 350°F. (177° C.). Can be diluted with hydrocarbon solvents or oil. Alpha3488 - 75 to 80% active organic acid-amine salt used to formulatenon-emulsifying corrosion inhibitors for use in drilling, producing,transporting, and refining of crude oil. Can be used in concentratedform or diluted (20 to 35% by volume) with hydrocarbon solvents forapplication purposes. Alpha 3489 - 75 to 80% active organic acid-aminesalt used to formulate corrosion inhibitors for use in drilling,producing, transporting, and refining of crude oil. Used as corrosionand scale preventives in oil systems, water floods, or water disposalsystems. Can be used in concentrated form or diluted with hydrocarbonsolvents. Alpha 3732C - 95 to 99% active organic acid-amine salt used toformulate thermally stable corrosion inhibitors for use in drilling,producing, transporting, and refining of crude oil. Used in oil and gaswells, oil transport systems, refineries, and water flood or disposalsystems. Can be used in concentrated form or diluted with hydrocarbonsolvents, aromatic or aliphatic, for application purposes. Effectiveagainst carbon dioxide, hydrogen sulfide, and oxygen. Alpha 3930 - 98 to100% active crude dimerized fatty acid to formulate corrosionpreventives for use in drilling, producing, transporting, and refiningof crude oil. Can be formulated with amides, amines, or imidazolines foruse as corrosion preventives, emulsifiers, wetting agents, or scalepreventives. Can be used in concentrated form or diluted for applicationpurposes in all types of oil systems. CI-850 (CE-1050) - Tall oildimer-trimer acid that is typically blended with imidazolines, amides,and other amine-based corrosion inhibitors extend film life and providecorrosion control properties in both sweet and sour environments.

Crude oil contains natural surfactants, which, when mixed with water,can emulsify the water into oil. The more common emulsion is waterdispersed in oil, but “reverse” emulsions (oil in water) can also occur.Emulsions raise the bottom sediment and water (BS and W) of oil and areoften very viscous. Emulsion breakers are a class of chemicals used toseparate emulsions (e.g. water in oil). They are commonly used in theprocessing of crude oil, which is typically produced along withsignificant quantities of saline water. This water (and salt) must beremoved from the crude oil prior to refining. If the majority of thewater and salt are not removed, significant corrosion problems can occurin the refining process. Emulsion breakers are typically based on thefollowing chemistry: acid catalysed phenol-formaldehyde resins; basecatalyzed; phenol-formaldehyde resins; epoxy resins; polyethyleneimines;polyamines; di-epoxides; or polyols. Commercially available emulsionbreakers are sold by Weatherford, such as those described in Table 2below.

TABLE 2 DB-904 - Amine-based demulsifier that provides a clean interfaceand clean water. More effective on mid-range API gravity crudes, thanpoly-based products. Can be used to treat oil-in- water emulsions. Therelative solubility number (RSN) is 12.5. DB-951 - Amine-baseddemulsifier that provides a clean interface and clean water. Moreeffective on mid-range API gravity crudes, than poly-based products. Canbe used to treat oil-in- water emulsions. The relative solubility number(RSN) is 10.0. DB-954 - Amylresin-based demulsifier that is effective inmixed and asphaltenic crudes. Effective in low to high gravity APIcrudes to provide primary water drop and drop entrained water. Therelative solubility number (RSN) is 11.3. DB-955 - Amyl resin-baseddemulsifier that is effective in mixed and asphaltenic crudes. Effectivein low to high gravity API crudes to provide primary water drop and dropentrained water. The relative solubility number (RSN) is 14.5. DB-958 -Amyl resin-based demulsifier that is effective in mixed and asphalteniccrudes. Effective in low to high gravity API crudes to provide primarywater drop and drop entrained water. The relative solubility number(RSN) is 16.0. DB-942 - Butyl resin-based demulsifier that is effectivein paraffinic and mixed crudes. Effective in low to high gravity APIcrudes to provide primary water drop and drop entrained water. Therelative solubility number (RSN) is 9.5. DB-945 - Butyl resin-baseddemulsifier that is effective in paraffinic and mixed crudes. Effectivein low to high gravity API crudes to provide primary water drop and dropentrained water. The relative solubility number (RSN) is 9.0. DB-934 -Nonyl resin-based demulsifier that is effective in naphthenic crudes.Effective in low to high gravity API crudes to provide primary waterdrop and drop entrained water. Nonyl resins are the most widely used ona global basis. The relative solubility number (RSN) is 15.0. DB-935 -Nonyl resin-based demulsifier that is effective in naphthenic crudes.Effective in low to high gravity API crudes to provide primary waterdrop and drop entrained water. Nonyl resins are the most widely used ona global basis. The relative solubility number (RSN) is 16.5. DB-946 -Nonyl resin-based demulsifier that is effective in naphthenic crudes.Effective in low to high gravity API crudes to provide primary waterdrop and drop entrained water. Nonyl resins are the most widely used ona global basis. The relative solubility number (RSN) is 10.5. DB-947 -Nonyl resin-based demulsifier that is effective in naphthenic crudes.Effective in low to high gravity API crudes to provide primary waterdrop and drop entrained water. Nonyl resins are the most widely used ona global basis. The relative solubility number (RSN) is 13.5. Alpha4068 - 60 to 65% active polymerized resin-ester-blend that functions asa demulsifier intermediate used to prepare formulas for treating crudeoil emulsions at wellheads, tank batteries, or other gathering points.Also used to prepare solutions for desalting of crude oil. Should bediluted with heavy aromatic naphtha, xylene, or other aromatic solventsfor improved performance. Alpha 4212 - 94 to 98% active triol fatty acidester that functions as a demulsifier intermediate used to prepareformulas for treating crude oil emulsions at wellheads, tank batteries,or other gathering points. Also used to prepare solutions for desaltingof crude oil. Should be diluted with heavy aromatic naphtha, xylene, orother aromatic solvents for improved performance. Alpha 4312 - 83 to 87%active triol adipate ester that functions as a demulsifier intermediateused to prepare formulas for treating crude oil emulsions at wellheads,tank batteries, or other gathering points. Also used to preparesolutions for desalting of crude oil. Should be diluted with heavyaromatic naphtha, xylene, or other aromatic solvents for improvedperformance. Alpha 4531 - 100% active triol fumarate ester thatfunctions as a demulsifier intermediate used to prepare formulas fortreating crude oil emulsions at wellheads, tank batteries, or othergathering points. Also used to prepare solutions for desalting of crudeoil. Should be diluted with heavy aromatic naphtha, xylene, or otheraromatic solvents for improved performance. DB-918 - Polyolester-baseddemulsifier used to treat loose emulsions providing a clean interfaceand clean water. The relative solubility number (RSN) is 7.5. DB-911 -Polyol-based demulsifier used to treat loose emulsions providing a cleaninterface and clean water. The relative solubility number (RSN) is 10.8.DB-938 - Polyol-based demulsifier used to treat loose emulsionsproviding a clean interface and clean water. The relative solubilitynumber (RSN) is 9.9. DB-961 - Polyol-based demulsifier used to treatloose emulsions providing a clean interface and clean water. Therelative solubility number (RSN) is 13.3. DB-964 - Polyol-baseddemulsifier used to treat loose emulsions providing a clean interfaceand clean water. Water-wets the solids, dropping them to the waterphase. Also used in desalter formulations. The relative solubilitynumber (RSN) is 17.5. DB-984 - Polyol-based demulsifier used to treatloose emulsions providing a clean interface and clean water. Water-wetsthe solids, dropping them to the water phase. Also used in desalterformulations. The relative solubility number (RSN) is 20.0. Alpha 2618 -55 to 60% active ammonium sulfonate used to prepare emulsion preventivesfor oil washes, removal of mud blocks, water blocks and emulsion blocks,and in workovers and chemical treatments. Usually diluted with water,xylene, methanol, or other alcohols. Alpha 4153 - 90 to 95% activeisopropylamine sulfonate that is used to prepare emulsion preventivesfor oil washes, removal of mud blocks, water blocks and emulsion blocks,and in workovers and chemical treatments. Usually diluted with water,methanol, xylene, or alcohols. Alpha 4180 - 65 to 70% active aminesulfonate used to prepare emulsion preventives for oil washes, removalof mud blocks, water blocks and emulsion blocks, and workovers andchemical treatments. Also functions as a dispersant for paraffinremoval. Usually diluted with heavy aromatic naphtha, xylene, oralcohols. Alpha 2919 - 98 to 100% active ethoxylated fatty oil that isused to formulate surfactants for water floods or water disposal systemsto clean solids, oil, and lower interfacial tension of oil and water toformation rock. Usually diluted in water, alcohols, or aromatic solventsfor applications. Alpha 4122 - 63 to 68% active polymerized resin esterof phenolic with an acrylate-anhydride polyglycol polymer that functionsas a demulsifier intermediate used to prepare formulas for treatingcrude oil emulsions at wellheads, tank batteries, or other gatheringpoints. Also used to prepare solutions for desalting crude oil. Shouldbe diluted with heavy aromatic naphtha, xylene, or other aromaticsolvents for improved performance. Alpha 4138 - 85 to 90% active blendof amine sulfonates, polyglycols, ketone, and terpene used to prepareemulsion preventives for oil washes, removal of mud blocks, water blocksand emulsion blocks, and in workovers and chemical treatments. Usuallydiluted with xylene, alcohol, or aromatic naphthas. Alpha 4400 - 80 to85% active complex mixture of amine sulfonates and polyglycols used toprepare emulsion preventives for oil or water washes and for theprevention of emulsions in workovers or chemical treatments. Usuallydiluted with heavy aromatic naphtha, xylene, or alcohols. Alpha 4670 -40 to 45% active blend of polymerized polyglycol and an oxyalkylatedalkyl phenolic resin terminated polyurea of a triol that functions as ademulsifier intermediate used to prepare formulas for treating crude oilemulsions at wellheads, tank batteries, or other gathering points. Alsoused to prepare solutions for desalting crude oil. Should be dilutedwith heavy aromatic naphtha, xylene, or other aromatic solvents forimproved performance. ALPHA-BREAK (emulsion breaker, Weatherford) 105 -Oil-soluble demulsifying surfactant containing an ammonium salt of anaphthalene sulfonate in aromatic solvents that effectively “breaks”oilfield emulsions. Proper concentration can be determined based on arelatively simple bottle test. ALPHA-BREAK 400 (emulsion breaker,Weatherford) - Oil-soluble demulsifying surfactant containing anammonium salt of a naphthalene sulfonate, with an ethoxylated resin inaromatic solvents that effectively “breaks” oilfield emuslions. Usually30 to 500 ppm is recommended, but the proper concentration can bedetermined based on a relatively simple bottle test. DB-928 - Specialtyblend demulsifier that speeds water drop and allows treatment at lowertemperature and lower rates when used in combination with otherdemulsifiers. The relative solubility number (RSN) is 5.5. DB-937 -Specialty blend demulsifier that speeds water drop and allows treatmentat lower temperature and lower rates when used in combination with otherdemulsifiers. The relative solubility number (RSN) is 7.8. DB-939 -Specialty blend demulsifier that speeds water drop and allows treatmentat lower temperature and lower rates when used in combination with otherdemulsifiers. The relative solubility number (RSN) is 9.9. DB-941 - 40to 45% active blend of phenol formaldehyde resin and polyamine thatfunctions as a demulsifier for treating crude oil emulsions atwellheads, tank batteries, or other gathering points. Speeds the waterdrop from the emulsion and allows treatment at lower temperatures. Canbe used in combination with other demulsifiers. The relative solubilitynumber (RSN) is 12.5. DB-9393 - Specialty blend demulsifier that speedswater drop and allows treatment at lower temperature and lower rateswhen used in combination with other demulsifiers. The relativesolubility number (RSN) is 5.0. DC-903 - Concentrated alkoxylatedalkylphenol formaldehyde resin blend that functions as a desalter anddemulsifier for medium to high gravity crude oils. Usually diluted 2 to3 times in solvents and applied at concentrations from 10 to 50 ppm.DC-904 - Concentrated alkoxylated alkylphenol formaldehyde resin blendthat functions as a desalter and demulsifier for low to medium gravitycrude oils. Usually diluted 2 to 3 times in solvents and applied atconcentrations from 10 to 50 ppm. DC-905 - Concentrated alkoxylatedalkylphenol formaldehyde resin blend that functions as a desalter anddemulsifier for medium to high gravity crude oils. Usually diluted 2-3times in solvents and applied at concentrations from 10-50 ppm. DC-907 -Concentrated alkoxylated alkylphenol formaldehyde resin blend thatfunctions as a desalter and demulsifier for low to medium gravity crudeoils. Usually diluted 2-3 times in solvents and applied atconcentrations from 10-50 ppm.

Hydrogen Sulfide (H₂S) is a poisonous gas that is deadly at highconcentrations and poses serious health threats at moderateconcentrations. Operating problems caused by H₂S can include severecorrosion and fouling, and injection-well plugging with iron sulfides.Hydrogen sulfide controllers are a class of compounds that react withH₂S to convert the H₂S or mercaptans into other sulfur compounds.Exemplary hydrogen sulfide controllers are oxidizers, such as peroxide,amine neutralizers, sodium hydroxide or a blend of sodium and potassiumhydroxide, triazine-based chemistry, metal scavengers, etc. Commerciallyavailable hydrogen sulfide controllers are sold by Weatherford, such asthose described in Table 3 below.

TABLE 3 Alpha ONE - A 50 to 55 percent active aqueous, polymeric,amino-alcohol solution designed to be effective in drilling-fluidsystems as both a H₂S converter and corrosion inhibitor. Temperaturestable, it can be used as an additive in acid stimulation treatments.The scavenging rate in a liquid mud system is 2.0 to 75.0 ppm per ppmsulfide. SULFACLEAR 8199 (hydrogen sulfide controller, Weatherford) -A72 to 76 percent active, oil- soluble, cyclic, tertiary amine designedas a H₂S scavenger for gas systems. It can be diluted with aromaticsolvents, diesel, kerosene or other low-molecular-weight alcohols. Thescavenging rate is 1.0 to 5.0 ppm per ppm H₂S in gas systems. SULFACLEAR8211 (hydrogen sulfide controller, Weatherford) - A33 percent active,aqueous, cyclic, tertiary amine solution designed as a sulfide scavengerfor gas and water. The scavenging rate in gas is 1.0 to 8.0 ppm per ppmsulfide. In water-based systems, the ratio is 6.0 to 15.0 ppm per ppmH₂S. It can be diluted with methanol or water for application purposes.SULFACLEAR 8250 (hydrogen sulfide controller, Weatherford) - A33 percentactive, aqueous amine solution designed as a sulfide scavenger for gasand water. The scavenging rate in gas is 1.0-8.0 ppm per ppm sulfide. Inwater based systems the ratio is 6.0 to 15.0 ppm per ppm H₂S. It can bediluted with methanol or water for application purposes. SULFACLEAR 8311(hydrogen sulfide controller, Weatherford) - A 47 percent active,aqueous cyclic tertiary amine solution designed as a sulfide scavengerfor gas treating applications. This solution is ideally suited fortreating gas with high CO₂ concentrations. SULFACLEAR 8411C (hydrogensulfide controller, Weatherford) - A 50 percent active, aqueous, cyclic,tertiary amine solution designed as a sulfide scavenger for water. Thescavenging rate in water systems is 2.0 to 20.0 ppm per ppm sulfide. Fortreatment of H₂S in gas or crude oil, concentrations range from 1.0 to10.0 ppm per ppm H₂S. It can be diluted with water or methanol.SULFACLEAR 8411HC (hydrogen sulfide controller, Weatherford) - An 80percent active, aqueous, cyclic, tertiary amine designed as a sulfidescavenger for water. The scavenging rate in water systems is 2.0 to 20.0ppm per ppm sulfide. This solution is used for treatment of H₂S in gasconcentrations range from 1.0 to 10.0 ppm per ppm H₂S. It can be dilutedwith water or methanol. SULFACLEAR 8419 (hydrogen sulfide controller,Weatherford) - A 47 percent active, aqueous, cyclic, tertiary aminesolution designed as a sulfide scavenger for gas treating applications.This solution is ideally suited for treating gas with high CO₂concentrations. Usually used in bubble tower applications, it has ascavenging rate of 3.0 to 10.0 ppm per ppm sulfide. SULFACLEAR 8495(hydrogen sulfide controller, Weatherford) - A 63 percent active,aqueous, cyclic, tertiary amine benzyl quaternary blended compoundsolution designed as a H₂Sscavenger and water clarifier. The scavengingrate in water systems is 2.0 to 20.0 ppm per ppm H₂S. SULFACLEAR 8640(hydrogen sulfide controller, Weatherford) - A patented, 50 percentactive, aqueous, cyclic, tertiary, amine polymer blend containingsurfactants designed as a H₂S and mercaptan scavenger for water or gassystems. The scavenging rate is 1.0 to 4.0 ppm per ppm H₂S. It can bediluted with methanol, glycols or water. SULFACLEAR 8640HC (hydrogensulfide controller, Weatherford) - An 80 percent active, aqueous,cyclic, tertiary amine polymer blend containing surfactants designed asa H₂S scavenger for water or gas systems. The scavenging rate is 1.0 to4.0 ppm per ppm H₂S. It can be diluted with methanol, glycols, or water.SULFACLEAR 8649 (hydrogen sulfide controller, Weatherford) - A patented,50 percent active, aqueous, cyclic, tertiary amine polymer-blend resinsolution that contains surfactants and functions as a H₂S and mercaptanscavenger for water or gas systems. The scavenging rate is 1.0 to 4.0ppm per ppm H₂S in water systems, and 4.0 to 20.0 ppm per ppm H₂S in gassystems. It can be diluted with methanol, glycols or water. SULFACLEAR8849 (hydrogen sulfide controller, Weatherford) - A 100 percent active,oil- soluble alkyl amine-formaldehyde condensate that functions as a H₂Sscavenger for gas, oil and multiphase systems. The scavenging rate is1.0 to 5.0 ppm per ppm H₂S. It can be diluted with aromatic solvents,diesel, kerosene or other low-molecular-weight alcohols.

Most crude oils contain paraffin in solution, and cooling causesparaffin crystals to clump together and build up on productionequipment. Left untreated, the buildup will eventually shut off the flowof oil by completely plugging tubing and flow lines. Paraffin controladditives are a class of compounds that help prevent or minimize theamount of paraffin deposits formed. Commercially available hydrogensulfide controllers are sold by Weatherford, such as those described inTable 4 below.

TABLE 4 Alpha 5242 - 40% active acidic copolymer in aromatic naphthathat functions as a wax crystal modifier for crude oils and heavy fueloils. Can be used neat or diluted (20% by volume) with heavy aromaticnaphtha, toluene, or xylene for continuous or batch injection. Normallyapplied at concentrations of 100 to 2000 ppm to crude above itscrystallization point or heated and mixed. Alpha 5445 - 95 to 100%active alkylated polyester amide, copolymer, and wax composition thatfunctions as a pour point depressant for crude oils and heavy oils. Canbe used neat, when hot, or diluted with heavy aromatic naphtha, toluene,or xylene for continuous or batch injection. Normally applied atconcentrations of 100 to 2000 ppm to crude above its crystallizationpoint or heated and mixed. Alpha 5482 - 73 to 77% active alkylatedpolyester in xylene that functions as a wax crystal modifier for crudeoils and heavy fuel oils. Can be used neat or diluted with heavyaromatic naphtha, toluene, or xylene for continuous or batch injection.Normally applied at concentrations of 100 to 2000 ppm to crude above itscrystallization point or heated and mixed. Alpha 5603C - 100% activealkylated polyester that functions as a wax crystal modifier for crudeoils and heavy fuel oils. Can be diluted (20% by volume) with heavyaromatic naphtha, toluene, or xylene for continuous or batch injection.Normally applied at concentrations of 100 to 2000 ppm to crude above itscrystallization point or heated and mixed. Alpha 5609 - 40% activealkylated polyester amide/imide that functions as a wax crystal modifierfor crude oils and heavy fuel oils. Can be used neat or diluted withheavy aromatic naphtha, toluene, or xylene for continuous or batchinjection. Normally applied at concentrations of 100 to 2000 ppm tocrude above its crystallization point or heated and mixed. Alpha 7526 -40% active amine sulfonate mixture used as a pour point depressant todisperse and remove paraffin. Can be used in its concentrated form ordiluted with heavy aromatic naphtha, diesel fuel, xylene, or alcoholsfor ease of handling. Can be used in pipelines, producing wells, oilhandling and storage equipment, and in refineries. Alpha 7527 - 30%active amine sulfonate mixture used as a pour point depressant todisperse and remove paraffin. Can be used in its concentrated form ordiluted with heavy aromatic naphtha, diesel fuel, xylene, or alcoholsfor ease of handling. Can be used in producing wells, oil handling andstorage equipment, and in refineries. PARA CLEAR D290 (Paraffin controladditive, Weatherford) - Contains synergistic blends of surfactants,amines, alcohols and diols to not only penetrate and disperse theparaffin, but also isolate the paraffin molecules by forming a coatingaround them to inhibit their growth. Should be mixed at 3 to 10% infresh water, pumped down the casing annulus, and allowed to contact theparaffin for 12 to 24 hours. PARA CLEAR D500 (Paraffin control additive,Weatherford) - Contains synergistic blends of surfactants, amines,alcohols and diols to not only penetrate and disperse the paraffin, butalso isolate the paraffin molecules by forming a coating around them toinhibit their growth. Should be mixed at 10 to 15% in fresh water andallowed to contact the paraffin for 12 to 24 hours. PARA CLEAR D700(Paraffin control additive, Weatherford) - Synergistic blend ofsurfactants and amines in an environmentally friendly fluid that notonly disperses paraffin molecules, but also inhibits their growth.Contains no BTX solvents and is normally mixed at 10 to 15% by volume infresh water. PARA CLEAR HWD-106 (Paraffin control additive,Weatherford) - Composed of ionic and non-ionic components mixed inselective solvents to remove accumulated paraffin deposits whilepreventing the paraffin from separating out of the oil phase. Leaves thesurface of the pipe “water-wet”, thus retarding the re-deposition ofparaffin for a period of time. Should be mixed at 10 to 15% in freshwater and allowed to contact the paraffin for 12 to 24 hours. ParaClean26 - Amine sulfonate mixture used to disperse and remove paraffindeposits in pipelines, gathering systems, oil handling and storageequipment, and in refineries. Can be used in its concentrated form orcan be diluted with heavy aromatic naphtha, diesel fuel, xylene, oralcohols for ease of handling. Particularly effective in pipelinepigging operations as a single step product. ParaClean 27C - Aminesulfonate mixture used to dissolve, disperse and remove paraffindeposits in pipelines, gathering systems, oil handling and storageequipment, and in refineries. Can be used in its concentrated form orcan be diluted with heavy aromatic naphtha, diesel fuel, xylene, oralcohols for ease of handling. Most effective when used in a continuoustreatment alone or in advance of a pigging procedure. PD-816 - 100%active blend of amines, alcohols, and sulfonates used to formulate bothoil- and water-soluble paraffin dispersants to treat paraffenic,asphaltenic, and/or naphthenic crude oil production.

Scale occurs because the minerals in produced water exceed theirsaturation limit as temperatures and pressures change. Scale can vary inappearance from hard crystalline material to soft, friable material andthe deposits can contain other minerals and impurities such as paraffin,salt and iron. The most common of the mineral scales is calciumcarbonate. Other common mineral deposits include calcium sulfate(gypsum), strontium sulfate, and barium sulfate. Scale inhibitors areused to prevent these deposits from forming. There are three commontypes of chemical compounds used for this purpose, phosphate esters,phosphonates, and acid polymers. Commercially available hydrogen sulfidecontrollers are sold by Weatherford, such as those described in Table 5below.

TABLE 5 Alpha 2003 and Alpha 2004 - are concentrated 95- to 100-percentactive alkyl-nonylphenol- phosphate-ester-acid anionic surfactants withmultifunctional abilities. They can be formulated to perform as anemulsifier, wetting agent, antifoulant, cleaner, or detergent. Theseproducts can be used in foam and air-mist drilling systems withoutoffsetting drilling fluid properties. Alpha 2401 - is a 40- to45-percent active bishexamethylenetriamine pentamethylene phosphonicacid sodium salt concentrate used to formulate scale preventives fortreatment of calcium carbonate, calcium, barium, and strontium sulfate.Alpha 2240 - is a 70- to 80-percent active hydroxyamino phosphate esterconcentrate used to formulate scale preventives for squeeze orcontinuous treatment of calcium carbonate, calcium, barium, andstrontium sulfate. Alpha 2240-70 - is a 57- to 61-percent activehydroxyamino phosphate ester concentrate used to formulate scalepreventives for squeeze or continuous treatment of calcium carbonate,calcium, barium, and strontium sulfate. Alpha 2247 is a 63- to67-percent active hydroxyamino phosphate ester sodium salt concentrateused to formulate scale preventives for treatment of calcium carbonate,calcium, barium, and strontium sulfate. Alpha 2290 - is a 90- to100-percent active alkyl phosphate ester acid corrosion preventive usedin water-based drilling systems. Alpha 2408 - is a 35- to 45-percentactive sodium salt of a modified diamine phosphonate concentrate used toformulate scale preventives. Alpha 2801 - is a 48- to 52-percent activebishexamethylenetriamine pentamethylene phosphonic acid used as aconcentrate for treating calcium and magnesium carbonate, calcium,barium, and strontium sulfate. Alpha 2803 - is a 48- to 52-percentactive diethylenetriamine pentamethylene phosphonic acid to formulatescale preventives for treatment of calcium and magnesium carbonate,calcium sulfate, and barium scales. Alpha 2807 - is a 48- to 52-percentactive concentrate of phosphonate and ether diamines, triamines, andtetramines used to formulate scale preventives for treating calcium andmagnesium carbonate, calcium, barium, strontium sulfate, and ironscales. Alpha 2867 - is a 38- to 42-percent active ammonium salt ofether diamine, triamine, and tetramine phosphonate, used to formulatescale preventives for treatment of calcium and magnesium carbonate,calcium, barium, strontium sulfate, and iron scales. Alpha 2771 - 50 to55% active sodium salt of complex polyacrylate designed as a scaleinhibitor for calcium and magnesium carbonate, calcium, barium andstrontium sulfate, and iron scales in water systems. Also functions as adispersant and sludge conditioner in boilers. Can be diluted with wateror water and antifreeze agents before use for ease of handling. J-Poly101A - 50% active polyacrylate scale inhibitor. Effective againstcalcium carbonate, calcium sulfate, and certain iron scales. Stable athigh temperatures and is slightly acidic (pH 3-4). SCALECLEAR A100(Scale inhibitor, Weatherford) - is a liquid blend containing bothorganic and mineral acids, corrosion inhibitors, and amphotericsurfactants used to dissolve carbonate, iron-sulfide, and iron-oxidescales. SCALECLEAR CSP (Scale inhibitor, Weatherford) - is a solidcontrolled-release scale preventive containing three formulations offused sodium-calcium phosphate glass, each with a guaranteed minimumphosphorus pentoxide content of 68 percent, designed for treatment ofcalcium carbonate, calcium, barium, and strontium sulfate. NA-MINUS 55(Scale inhibitor, Weatherford) - Liquid formulation of imido polyalkylamides used to inhibit precipitation of sodium chloride salt from highchloride brines. Allows treatment fluids to carry very high saltsaturations up to 40%. Generally, 5% by volume of fresh water isrecommended for batch treatments. For continuous treatment, 250 to 1000ppm (parts per million) neat chemical should be added to the brine.NA-MINUS (Scale inhibitor, Weatherford) - Liquid formulation of aminoacid amides that controls salt deposition over the wide temperature andpressure ranges encountered from the bottom of the hole to the surfacein producing wells. Dosage requirements will vary with brine,temperature changes, solids concentration, pH and equilibrium time. Forcontinuous treatment, 250 to 1000 ppm (parts per million) neat chemicalshould be added to the brine.

Aspects of the invention are accomplished using a porous substrate sprayionization probe coupled to a mass spectrometer, such as a miniaturemass spectrometer. In certain embodiments, the miniature massspectrometer includes a discontinuous atmospheric pressure interface(DAPI), which is discussed in greater detail below. In certainembodiments, the porous substrate spray probe coupled to a massspectrometer is used to analyze, identify, and quantify analytes (e.g.,corrosion inhibitors) in crude oil. Porous substrate spray allows theanalysis to occur without any sample preparation or pre-purification. Inmethods of the invention, crude oil is taken from a source, e.g., apipeline, and in an unmodified form, is spotted directed onto the paperspray probe. Such a set-up is exemplified in FIG. 1. Solvent is appliedand the spray generated from the paper probe is analyzed (FIG. 1).

Methods of the invention can be conducted in an ambient environment andallow for ambient ionization mass spectrometry of crude oil samples,i.e., ionization is performed on unmodified samples in air. Thisapproach provides almost instantaneous data while eliminating orminimizing sample preparation or sample pre-purification. Accordingly,methods of the invention allow for rapid and efficient in-fieldtechniques for analyzing an analyte in crude oil, such as monitoring ofcorrosion inhibitors in the oil in transmission pipelines. Ambientionization is described for example in Nemes et al. (Trends in Anal.Chem., 2012, 34, 22-34), Harris et al. (Anal. Chem., 2011, 83,4508-4538), Huang et al., (Ann. Rev. Anal. Chem., 2010, 3, 43-65), Ifaet al. (Analyst, 2010, 135, 669-681), Cooks et al. (Science, 2006, 311,1566-1570, Cooks et al. (Faraday Discussions, 2011, 149, 247-267),Venter et al. (Anal. Chem., 2008, 27, 284-290), Harris et al. (Analyst,2008, 133, 1297-1301), Takats et al. (Science, 2004, 306, 471-473), Codyet al. (Anal. Chem., 2005, 77, 2297-2901), and Ratcliffe et al. (Anal.Chem., 2007, 79, 6094), the content of each of which is incorporated byreference herein in its entirety.

Porous substrate spray is further described in Ouyang et al. (U.S.patent application serial number 2012/0119079), the content of which areincorporated by reference herein in its entirety. The paper sprayionization method is soft (it deposits little internal energy into ions)and amenable to the analysis of small and large molecules ranging fromsimple organics to large biomolecules (Wang et al., AngewChemie-International Edition., 2010, 49, 877-880; Zhang et al., Anal.Chem., 2012, 84(2) 931-938; Yang et al., Anal & Bio. Chem., 2012, 404,1389-1397, and Zhang et al., Analyst, 2012, 137, 2556-2558).

In the porous substrate spray embodiment, the sample is spotted onto aporous substrate, e.g., paper (or other solid medium). The poroussubstrate may be cut to a fine point. In certain embodiments, the poroussubstrate tapers to a microscopic tip, such as a carbon nanotube. Theporous substrate is wetted with solvent and charged liquid droplets areemitted from the porous substrate tip when a high DC voltage (±3.5 kV)is applied. Without being limited by any particular theory or mechanismof action, it is believed that droplet emission occurs by field emission(Espy et al., Int. J. Mass Spectrom, 2012, 325-327, 167-171). Subsequention generation from the charged droplets is thought to followelectrospray-like mechanisms (Crotti et al., Euro. J. Mass Spectrom,2011, 17, 85-99). Porous substrate ionization is described in greaterdetail below.

In certain embodiments, porous substrate spray ionization is combinedwith a portable mass spectrometer for rapid, in-situ analysis ofcorrosion inhibitor actives (i.e. alkyl ammonium salts) in petroleumoil. It is believed that tetradodecylammonium bromide andbenzylhexadecyldimethylammonium chloride are representative of theactive components in many corrosion inhibitor formulations (Quraishi etal., Am. Oil Chem. Soc., 2000, 77, 1107-1111, Treybig et al., U.S. Pat.No. 4,957,640, Derek et al., U.S. Pat. No. 4,235,838, and Young et al.,U.S. Pat. No. 6,645,399). Both compounds contain long hydrophobic alkylchains that allow them to dissolve in oil. The data in the Example belowshow that <1 ng/μL of quaternary ammonium salt in 1 μL oil (e.g., pumpoil) placed onto paper can be detected easily using either a commercialbench-top or a miniature mass spectrometer. This concentration (<100ppb) of the active corrosion inhibitor is well below the reportedminimum effective range of concentrations of these inhibitors, which is50-200 ppm (Viswanathan, Corrosion Science, 2010, 2, 6-12; and Boris etal., NACE International Corrosion Conference and Exponent, 2009, No09573). The data further demonstrate that in-situ analyte(s)identification was achieved by analyzing the fragmentation patterns ofthe corrosion inhibitors generated using tandem mass spectrometry(MS/MS; Jackson et al., Eur. Mass Spectrom., 1997, 3, 113-120; Jacksonet al., Int. J. Mass Spectrom., 2004, 238, 265-277; Jackson et al.,Rapid Commun. Mass Spectrom., 2006, 20, 2717-2727; (Busch et al., MassSpectrometry/Mass Spectrometry: Techniques and applications of TandemMass Spectrometry, VCH Publishers Inc., New York, 1988).

Miniature Mass Spectrometers

As mentioned above, the mass spectrometer may be for a bench-top orlab-scale mass spectrometer or a miniature mass spectrometer. Anexemplary miniature mass spectrometer is described, for example in Gaoet al. (Z. Anal. Chem. 2006, 78, 5994-6002), the content of which isincorporated by reference herein in its entirety In comparison with thepumping system used for lab-scale instruments with thousands watts ofpower, miniature mass spectrometers generally have smaller pumpingsystems, such as a 18 W pumping system with only a 5 L/min (0.3 m3/hr)diaphragm pump and a 11 L/s turbo pump for the system described in Gaoet al. Other exemplary miniature mass spectrometers are described forexample in Gao et al. (Anal. Chem., 80:7198-7205, 2008), Hou et al.(Anal. Chem., 83:1857-1861, 2011), and Sokol et al. (Int. J. MassSpectrom., 2011, 306, 187-195), the content of each of which isincorporated herein by reference in its entirety. Miniature massspectrometers are also described, for example in Xu et al. (JALA, 2010,15, 433-439); Ouyang et al. (Anal. Chem., 2009, 81, 2421-2425); Ouyanget al. (Ann. Rev. Anal. Chem., 2009, 2, 187-214); Sanders et al. (Euro.J. Mass Spectrom., 2009, 16, 11-20); Gao et al. (Anal. Chem., 2006,78(17), 5994-6002); Mulligan et al. (Chem.Com., 2006, 1709-1711); andFico et al. (Anal. Chem., 2007, 79, 8076-8082).), the content of each ofwhich is incorporated herein by reference in its entirety.

Ionization Using Wetted Porous Material

Probes comprised of porous material that is wetted to produce ions aredescribed in Ouyang et al. (U.S. patent application number 2012/0119079and PCT application number PCT/US10/32881), the content of each of whichis incorporated by reference herein in its entirety. Exemplary probesare shown in FIGS. 14A-B. Porous materials, such as paper (e.g. filterpaper or chromatographic paper) or other similar materials are used tohold and transfer liquids and solids, and ions are generated directlyfrom the edges of the material when a high electric voltage is appliedto the material. The porous material is kept discrete (i.e., separate ordisconnected) from a flow of solvent, such as a continuous flow ofsolvent. Instead, sample is either spotted onto the porous material orswabbed onto it from a surface including the sample. The spotted orswabbed sample is then connected to a high voltage source to produceions of the sample which are subsequently mass analyzed. The sample istransported through the porous material without the need of a separatesolvent flow. Pneumatic assistance is not required to transport theanalyte; rather, a voltage is simply applied to the porous material thatis held in front of a mass spectrometer.

In certain embodiments, the porous material is any cellulose-basedmaterial. In other embodiments, the porous material is a non-metallicporous material, such as cotton, linen wool, synthetic textiles, orplant tissue. In still other embodiments, the porous material is paper.Advantages of paper include: cost (paper is inexpensive); it is fullycommercialized and its physical and chemical properties can be adjusted;it can filter particulates (cells and dusts) from liquid samples; it iseasily shaped (e.g., easy to cut, tear, or fold); liquids flow in itunder capillary action (e.g., without external pumping and/or a powersupply); and it is disposable.

In certain embodiments, the porous material is integrated with a solidtip having a macroscopic angle that is optimized for spray. In theseembodiments, the porous material is used for filtration,pre-concentration, and wicking of the solvent containing the analytesfor spray at the solid type.

In particular embodiments, the porous material is filter paper.Exemplary filter papers include cellulose filter paper, ashless filterpaper, nitrocellulose paper, glass microfiber filter paper, andpolyethylene paper. Filter paper having any pore size may be used.Exemplary pore sizes include Grade 1 (11 μm), Grade 2 (8 μm), Grade 595(4-7 μm), and Grade 6 (3 μm). Pore size will not only influence thetransport of liquid inside the spray materials, but could also affectthe formation of the Taylor cone at the tip. The optimum pore size willgenerate a stable Taylor cone and reduce liquid evaporation. The poresize of the filter paper is also an important parameter in filtration,i.e., the paper acts as an online pretreatment device. Commerciallyavailable ultra-filtration membranes of regenerated cellulose, with poresizes in the low nm range, are designed to retain particles as small as1000 Da. Ultra filtration membranes can be commercially obtained withmolecular weight cutoffs ranging from 1000 Da to 100,000 Da.

Probes of the invention work well for the generation of micron scaledroplets simply based on using the high electric field generated at anedge of the porous material. In particular embodiments, the porousmaterial is shaped to have a macroscopically sharp point, such as apoint of a triangle, for ion generation. Probes of the invention mayhave different tip widths. In certain embodiments, the probe tip widthis at least about 5 μm or wider, at least about 10 μm or wider, at leastabout 50 μm or wider, at least about 150 μm or wider, at least about 250μm or wider, at least about 350 μm or wider, at least about 400μ orwider, at least about 450 μm or wider, etc. In particular embodiments,the tip width is at least 350 μm or wider. In other embodiments, theprobe tip width is about 400 μm. In other embodiments, probes of theinvention have a three dimensional shape, such as a conical shape.

As mentioned above, no pneumatic assistance is required to transport thedroplets. Ambient ionization of analytes is realized on the basis ofthese charged droplets, offering a simple and convenient approach formass analysis of solution-phase samples. Sample solution is directlyapplied on the porous material held in front of an inlet of a massspectrometer without any pretreatment. Then the ambient ionization isperformed by applying a high potential on the wetted porous material. Incertain embodiments, the porous material is paper, which is a type ofporous material that contains numerical pores and microchannels forliquid transport. The pores and microchannels also allow the paper toact as a filter device, which is beneficial for analyzing physicallydirty or contaminated samples. In other embodiments, the porous materialis treated to produce microchannels in the porous material or to enhancethe properties of the material for use as a probe of the invention. Forexample, paper may undergo a patterned silanization process to producemicrochannels or structures on the paper. Such processes involve, forexample, exposing the surface of the paper totridecafluoro-1,1,2,2-tetrahydrooctyl-1-trichlorosilane to result insilanization of the paper.

In other embodiments, a soft lithography process is used to producemicrochannels in the porous material or to enhance the properties of thematerial for use as a probe of the invention. In other embodiments,hydrophobic trapping regions are created in the paper to pre-concentrateless hydrophilic compounds. Hydrophobic regions may be patterned ontopaper by using photolithography, printing methods or plasma treatment todefine hydrophilic channels with lateral features of 200˜1000 μm. SeeMartinez et al. (Angew. Chem. Int. Ed. 2007, 46, 1318-1320); Martinez etal. (Proc. Natl Acad. Sci. USA 2008, 105, 19606-19611); Abe et al.(Anal. Chem. 2008, 80, 6928-6934); Bruzewicz et al. (Anal. Chem. 2008,80, 3387-3392); Martinez et al. (Lab Chip 2008, 8, 2146-2150); and Li etal. (Anal. Chem. 2008, 80, 9131-9134), the content of each of which isincorporated by reference herein in its entirety. Liquid samples loadedonto such a paper-based device can travel along the hydrophilic channelsdriven by capillary action.

Another application of the modified surface is to separate orconcentrate compounds according to their different affinities with thesurface and with the solution. Some compounds are preferably absorbed onthe surface while other chemicals in the matrix prefer to stay withinthe aqueous phase. Through washing, sample matrix can be removed whilecompounds of interest remain on the surface. The compounds of interestcan be removed from the surface at a later point in time by otherhigh-affinity solvents. Repeating the process helps desalt and alsoconcentrate the original sample.

In certain embodiments, chemicals are applied to the porous material tomodify the chemical properties of the porous material. For example,chemicals can be applied that allow differential retention of samplecomponents with different chemical properties. Additionally, chemicalscan be applied that minimize salt and matrix effects. In otherembodiments, acidic or basic compounds are added to the porous materialto adjust the pH of the sample upon spotting. Adjusting the pH may beparticularly useful for improved analysis of biological fluids, such asblood. Additionally, chemicals can be applied that allow for on-linechemical derivatization of selected analytes, for example to convert anon-polar compound to a salt for efficient electrospray ionization.

In certain embodiments, the chemical applied to modify the porousmaterial is an internal standard. The internal standard can beincorporated into the material and released at known rates duringsolvent flow in order to provide an internal standard for quantitativeanalysis. In other embodiments, the porous material is modified with achemical that allows for pre-separation and pre-concentration ofanalytes of interest prior to mass spectrum analysis.

Any solvents may be used that are compatible with mass spectrometryanalysis. In particular embodiments, favorable solvents will be thosethat are also used for electrospray ionization. Exemplary solventsinclude combinations of water, methanol, acetonitrile, and THF. Theorganic content (proportion of methanol, acetonitrile, etc. to water),the pH, and volatile salt (e.g. ammonium acetate) may be varieddepending on the sample to be analyzed. For example, basic moleculeslike the drug imatinib are extracted and ionized more efficiently at alower pH. Molecules without an ionizable group but with a number ofcarbonyl groups, like sirolimus, ionize better with an ammonium salt inthe solvent due to adduct formation.

Discontinuous Atmospheric Pressure Interface (DAPI)

In certain embodiments, a discontinuous atmospheric pressure interface(DAPI) is used with the bench-top or miniature mass spectrometer.Discontinuous atmospheric interfaces are described in Ouyang et al.(U.S. Pat. No. 8,304,718 and PCT application number PCT/US2008/065245),the content of each of which is incorporated by reference herein in itsentirety.

An exemplary DAPI is shown in FIG. 15. The concept of the DAPI is toopen its channel during ion introduction and then close it forsubsequent mass analysis during each scan. An ion transfer channel witha much bigger flow conductance can be allowed for a DAPI than for atraditional continuous API. The pressure inside the manifold temporarilyincreases significantly when the channel is opened for maximum ionintroduction. All high voltages can be shut off and only low voltage RFis on for trapping of the ions during this period. After the ionintroduction, the channel is closed and the pressure can decrease over aperiod of time to reach the optimal pressure for further ionmanipulation or mass analysis when the high voltages can be is turned onand the RF can be scanned to high voltage for mass analysis.

A DAPI opens and shuts down the airflow in a controlled fashion. Thepressure inside the vacuum manifold increases when the DAPI opens anddecreases when it closes. The combination of a DAPI with a trappingdevice, which can be a mass analyzer or an intermediate stage storagedevice, allows maximum introduction of an ion package into a system witha given pumping capacity.

Much larger openings can be used for the pressure constrainingcomponents in the DAPI in the new discontinuous introduction mode.During the short period when the DAPI is opened, the ion trapping deviceis operated in the trapping mode with a low RF voltage to store theincoming ions; at the same time the high voltages on other components,such as conversion dynode or electron multiplier, are shut off to avoiddamage to those device and electronics at the higher pressures. The DAPIcan then be closed to allow the pressure inside the manifold to dropback to the optimum value for mass analysis, at which time the ions aremass analyzed in the trap or transferred to another mass analyzer withinthe vacuum system for mass analysis. This two-pressure mode of operationenabled by operation of the DAPI in a discontinuous fashion maximizesion introduction as well as optimizing conditions for the mass analysiswith a given pumping capacity.

The design goal is to have largest opening while keeping the optimumvacuum pressure for the mass analyzer, which is between 10⁻³ to 10⁻¹⁰torr depending the type of mass analyzer. The larger the opening in anatmospheric pressure interface, the higher is the ion current deliveredinto the vacuum system and hence to the mass analyzer.

An exemplary embodiment of a DAPI is described herein. The DAPI includesa pinch valve that is used to open and shut off a pathway in a siliconetube connecting regions at atmospheric pressure and in vacuum. Anormally-closed pinch valve (390NC24330, ASCO Valve Inc., Florham Park,N.J.) is used to control the opening of the vacuum manifold toatmospheric pressure region. Two stainless steel capillaries areconnected to the piece of silicone plastic tubing, the open/closedstatus of which is controlled by the pinch valve. The stainless steelcapillary connecting to the atmosphere is the flow restricting element,and has an ID of 250 μm, an OD of 1.6 mm ( 1/16″) and a length of 10 cm.The stainless steel capillary on the vacuum side has an ID of 1.0 mm, anOD of 1.6 mm ( 1/16″) and a length of 5.0 cm. The plastic tubing has anID of 1/16″, an OD of ⅛″ and a length of 5.0 cm. Both stainless steelcapillaries are grounded. The pumping system of the mini 10 consists ofa two-stage diaphragm pump 1091-N84.0-8.99 (KNF Neuberger Inc., Trenton,N.J.) with pumping speed of 5 L/min (0.3 m3/hr) and a TPD011 hybridturbomolecular pump (Pfeiffer Vacuum Inc., Nashua, N.H.) with a pumpingspeed of 11 L/s.

When the pinch valve is constantly energized and the plastic tubing isconstantly open, the flow conductance is so high that the pressure invacuum manifold is above 30 torr with the diaphragm pump operating. Theion transfer efficiency was measured to be 0.2%, which is comparable toa lab-scale mass spectrometer with a continuous API. However, underthese conditions the TPD 011 turbomolecular pump cannot be turned on.When the pinch valve is de-energized, the plastic tubing is squeezedclosed and the turbo pump can then be turned on to pump the manifold toits ultimate pressure in the range of 1×10⁵ torr.

The sequence of operations for performing mass analysis using ion trapsusually includes, but is not limited to, ion introduction, ion coolingand RF scanning. After the manifold pressure is pumped down initially, ascan function is implemented to switch between open and closed modes forion introduction and mass analysis. During the ionization time, a 24 VDC is used to energize the pinch valve and the DAPI is open. Thepotential on the rectilinear ion trap (RIT) end electrode is also set toground during this period. A minimum response time for the pinch valveis found to be 10 ms and an ionization time between 15 ms and 30 ms isused for the characterization of the discontinuous DAPI. A cooling timebetween 250 ms to 500 ms is implemented after the DAPI is closed toallow the pressure to decrease and the ions to cool down via collisionswith background air molecules. The high voltage on the electronmultiplier is then turned on and the RF voltage is scanned for massanalysis. During the operation of the DAPI, the pressure change in themanifold can be monitored using the micro pirani vacuum gauge (MKS 925C,MKS Instruments, Inc. Wilmington, Mass.) on Mini 10.

INCORPORATION BY REFERENCE

References and citations to other documents, such as patents, patentapplications, patent publications, journals, books, papers, webcontents, have been made throughout this disclosure. All such documentsare hereby incorporated herein by reference in their entirety for allpurposes.

EQUIVALENTS

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The foregoingembodiments are therefore to be considered in all respects illustrativerather than limiting on the invention described herein. Scope of theinvention is thus indicated by the appended claims rather than by theforegoing description, and all changes which come within the meaning andrange of equivalency of the claims are therefore intended to be embracedtherein.

Examples

The Examples herein show implementation of porous substrate sprayambient ionization using a bench-top and portable mass spectrometer forthe detection of alkyl quaternary ammonium salts in a complex oilmatrix. These salts are commonly used as active components in theformulation of corrosion inhibitors. The active components of thecorrosion inhibitors were identified in oil and confirmed by theirfragmentation patterns recorded using tandem mass spectrometry (MS/MS).The cations of alkyl and benzyl-substituted quaternary ammonium saltsshowed characteristic neutral losses of C_(n)H_(2n) (n=carbon number ofthe longest chain) and C₇H₈, respectively. Individual quaternaryammonium compounds were detected at low concentrations (<1 ng/μL) andover a dynamic range of −5 ppb-500 ppb. Direct detection of thesecompounds in complex oil samples without prior sample preparation orpre-concentration was also demonstrated using a miniature massspectrometer at levels below 1 ng/μL.

Example 1: Chemicals, Reagents and Materials

Pure standard compounds with similar properties to the actives inquaternary ammonium corrosion inhibitors were purchased fromSigma-Aldrich (St. Louis, Mo.), namely, tetraoctylammonium bromide,tetradodecylammonium bromide, tetrahexylammonium bromide,tetrabutylammonium hexafluorophosphate, hexadecyltrimethylammoniumbromide, benzylhexadecyldimethylammonium chloride,hexadecyltrimethylammonium bromide, and a mixture of alkyldimethylbenzylammonium chloride ([C₆H₅CH₂N(CH₃)₂R]Cl where the alkyl group R ispredominantly n-C₁₂H₂₅ but also contains m/z 332 (C₁₄) and m/z 360 (C₁₆)homologs). Samples were dissolved in methanol to make a stock solutionat 1000 ppm. Working solutions were prepared by appropriate serialdilution with methanol/acetonitrile (1:1, v/v). Acetonitrile andmethanol (both HPLC grade) were obtained from Mallinckrodt Baker Inc.(Phillipsburg, N.J.). An artificial mixture consisting of each of themodel compounds at 100 ppb concentration was prepared so thatapproximately the same ion abundances were recorded. In order to mimicthe oilfield conditions, vacuum pump oil (Inland 19 PetroleumLubricating oil CAS Number: 64742-65-0) was used to dilute the stocksolution of the model compounds to 10 ppb concentration and this samplewas then analyzed without any pre-concentration or purification.Chromatography filter paper used for paper spray was purchased fromWhatman (Whatman, no. 1, Whatman International Ltd., Maidstone, UK).Methanol/acetonitrile (1:1, v/v) was used as the spray solvent for allthe paper spray experiment unless otherwise stated.

Example 2: Paper Spray Mass Spectrometry (PS-MS) Using a Bench-Top MassSpectrometer

Experiments were first performed using a Thermo LTQ linear ion trap massspectrometer (Thermo Scientific San Jose, Calif.) tuned for optimumdetection of the precursor ion of interest. The instrument was set torecord spectra in the automatic gain control mode for a maximum ion trapinjection time of 100 ms; three microscans were combined per spectrum.The main experimental parameters used were as follows: paper spraysolvent 10 4 of methanol/acetonitile (1:1, v/v); voltage applied to thepaper +3.5 kV in positive mode unless otherwise noted; capillarytemperature, 150° C.; tube lens voltage +65 V; capillary voltage, +15 V.Tandem mass spectrometry experiments were performed usingcollision-induced dissociation (CID) in order to confirm the presenceand identity of the analytes. These experiments were performed using anisolation window of 1.5 Thomson, (Th, i.e., m/z units) and 8-15%collision energy (manufacturer's unit) and the data recorded in theproduct ion scan mode (Schwartz et al., Anal. Chem., 1990, 62,1809-1818).

Example 3: Paper Spray Mass Spectrometry Using a Miniature MassSpectrometer

A paper spray ion source was interfaced, as shown in FIG. 1, to aminiature mass spectrometer the Mini 12.0 (Li et al., “Development andPerformance Characterization of a Personal Mass Spectrometry System”,61st ASMS Conference on Mass Spectrometry and Allied Topics,Minneapolis, Minn., Jun. 9-13, 2013, MP 330). A miniature massspectrometer is also described in PCT/US10/32881 and PCT/US2008/065245,the content of each of which is incorporated by reference herein in itsentirety. The mass analysis system, the vacuum system, the controlsystem and the detector are all integrated into a shoe-box sizedaluminum box. The overall instrument uses 65 W average power and weighs15 kg. The mass analyzer is a rectilinear ion trap (RIT; Sokol et al.,Int. J. Mass Spectrom., 2011, 306, 187-195; and Xu et al., JALA, 2010,15, 433-439) operating at a frequency of 1 MHz enclosed in a stainlesssteel manifold of 470 cm³ volume (Gao et al., Anal. Chem., 2006, 78(17),5994-6002). As a result of its simplified geometry and pressuretolerance, RITs have many advantages as a miniature mass analyzers as isevident in earlier applications (Sokol et al., Int. J. Mass Spectrom.,2011, 306, 187-195; Gao et al., Anal. Chem., 2006, 78(17), 5994-6002;and (March et al., Quadrupole Ion Trap Mass Spectrometry 2nd Edition,2005, pp. 167-1′76). The capability for tandem mass spectrometry isespecially valuable in enhancing the sensitivity and specificity ofmixture analysis. The operating pressure range was in the range 1×10⁻⁵Torr to ca. 5×10⁻² Torr, with mass analysis scans being performed in thelower range of pressures.

Example 4: Interface to the Mini 12.0 Mass Spectrometer

To achieve an adequate vacuum, a discontinuous atmospheric pressureinterface (DAPI; Ouyang, et al. Anal. Chem., 76, 4595-4605; Gao et al.,Anal. Chem., 80, 7198-7205; Gao et al., Anal. Chem., 2008, 80,4026-4032; and Gao et al., Int. J. Mass Spectrom., 2009, 283, 30-34) wasused to directly introduce ions and the accompanying ambient air intothe mass analyzer from the ambient environment. The pressure rises uponsample introduction and then falls again to levels suitable for massanalysis when the interface is closed. Unlike a conventional continuousion introduction technique, DAPI admits discrete pulses of ion/airmixture to reduce the gas load on the pumps. In each sampling period,the DAPI is opened for 10-20 ms under the control of a pulse valve.During this period, ions are pulsed into the vacuum system forsubsequent analysis. After the DAPI is closed, the neutral gas is pumpedaway so that the trapped ions can be mass analyzed. A DAPI can becoupled to a miniature mass spectrometer (Huang et al., Analyst, 2010,135, 705-711; and Soparawalla et al., Analyst, 2011, 136, 4392-4396).

Example 5: Paper Spray Ionization for In Situ Analysis

The paper spray ion emitter was held in front of the Mini 12.0 massspectrometer (Linfan et al., “Miniature Ambient Mass Analysis System”,manuscript in preparation) as shown in FIG. 1, to achieve rapid in situanalysis of untreated (i.e., unmodified) complex mixtures. Results fromthe in situ experiment using a miniature mass spectrometer were comparedwith the results from a typical bench-top commercial instrumentoperating in a typical lab setting.

Example 6: Tandem Mass Spectrometry

Mass-selected ions were fragmented through energetic collisions withneutral gas molecules using collision-induced dissociation (CID) in theMini 12.0 instrument. After the ions had been introduced by opening theDAPI valve for 15 ms, an 850 ms cooling time was provided to restore thevacuum before ion isolation. A broadband stored waveform inverse Fouriertransform (SWIFT) signal from 10 kHz to 500 kHz with a notch between 97kHz and 105 kHz was applied to the x electrodes of the RIT at anamplitude of 3.5 V_(p-p) for 175 ms to isolate the precursor ions ofinterest (the study was done at a Mathieu parameter q_(z) value of 0.185for each ion of interest and the RF amplitude was appropriately set toplace each ion at this value) (Guan et al., Int. J. Mass Spectrom. IonProcess, 1996, 157-158, 5-37). To perform CID, an AC signal of 0.45 V ata frequency of 102 kHz was then applied to the x electrodes of the RITfor 40 ms after the isolation step (Sokol et al., Int. J. MassSpectrom., 2011, 306, 187-195). The AC excitation signal was ramped from1.3 V_(p-p) to 6.6 V_(p-p) at 1000 mMHz for resonance ejection while theRF amplitude was ramped from 1 kV_(p-p) to 5 kV_(p-p) at 1 MHz in theacquisition time segment.

Example 7: Semi-Quantitative Analysis

The lower detection of limit (LOD) was determined as the concentrationthat produces a signal higher than 3 times of standard deviation plusthe mean value of the blank, in the MS/MS mode. Using a commerciallinear ion trap mass spectrometer, the detection limits of four modelcompounds in both neat solution and oil matrix were determined to be inthe low ppb level. Using the miniature ion trap (Mini 12), detectionlimits were ca. 10-50 times higher than those obtained using thecommercial instrument, as summarized in Table 1.

Quantitative analysis of the salt tetraoctylammonium bromide in oil wasachieved by calibration using another ammonium salt (tetraheptylammoniumbromide, 250 ppb) as internal standard. The signal intensity ratios ofthe most abundant MS/MS transitions were found to be linear in the rangefrom 5 ppb to 500 ppb. (y=0.0045x+0.00141, R²=0.9973), as shown in FIG.2. The measurements within this range had a relative standard deviationof <10% when three replicates were taken.

TABLE 1 Detection limits (LOD) of the analyzed quaternary ammonium modelcompounds in pg absolute LOD using commercial LOD using ion trap (pg)mini ion trap (pg) neat neat Compound solvent Oil matrix solvent Oilmatrix Tetraoctylammonium 0.9 1.1  81 184 bromide Tetrahexylammonium 0.69.5 notnot bromide available available Tetrabutylamonium 0.9 11.6 notnot hexafluorophosphate available available Benzylhexadecyldimethyl 10.227.6 282 472 ammonium chloride

Example 8: Quaternary Ammonium Salt Analysis Using Bench-Top Ion TrapMass Spectrometer

Two different groups of nitrogenous corrosion inhibitors (bothquaternary ammonium salts) were studied by paper spray massspectrometry. We first optimized paper spray ionization conditions usinga bench-top ion trap mass spectrometer to record positive ion data forthe quaternary ammonium corrosion inhibitor compounds. This wasperformed by applying 0.1 ng/μL (1 μL of 100 ppb solution) of thecorrosion inhibitor solution in vacuum pump oil, to a paper triangle,then adding acetonitrile/methanol solvent and recording data using theThermo LTQ. These mass spectra showed intact cations with little or nofragmentation or interference from the oil matrix (FIG. 2). Theremarkable absence of signal due to the oil components is consistentwith the high ionization efficiency of pre-charged organic salts, awell-known feature of many different types of ionization methods.Characterization of the individual intact cations was achieved by tandemmass spectrometry; for example, insert (ii) of FIG. 3A shows that CID ofthe intact tetraoctylammonium cation at m/z 466.6 gives two fragmentions (a major product at m/z 354.5 and minor product 352.5, with loss ofneutral octene (MW 112) and octane (MW 114), respectively (Sigsby etal., Organic Mass Spectrom., 1979, 14, 557). The stability and abundanceof the product ions allowed three-stage mass spectrometry (MS/MS/MS)experiments to be performed. In this particular case, CID of the production at m/z 345.5 yielded further fragment ions at m/z 242 (major) andm/z 240 (minor) through sequential losses of octene (presumably1-octene, CH₃—(CH₂)₅—CH═CH₂, MW 112) and octane (presumably n-octane,CH₃—(CH₂)₅—CH—CH₂, MW 114). Such multiple-stage MS experiments allowdefinitive confirmation of the identity of the analyte (Jackson et al.,Eur. Mass Spectrom., 1997, 3, 113-120; Jackson et al., Int. J. MassSpectrom., 2004, 238, 265-277; Jackson et al., Rapid Commun. MassSpectrom., 2006, 20, 2717-2727; and Busch et al., Mass Spectrometry/MassSpectrometry: Techniques and applications of Tandem Mass Spectrometry,VCH Publishers Inc., New York, 1988.)

Similarly, other model compounds including hexadecyltrimethylammoniumbromide, tetradodecylammonium bromide, tetrahexylammonium bromide, andbenzylhexadecyldimethylammonium chloride were analyzed by paper spray MSusing the Thermo LTQ commercial instrument, see FIGS. 7-10. Thenitrogenous corrosion inhibitors are available with differentcounterions, a property that influences the inhibition performance ofthe salts (Treybig, U.S. Pat. No. 4,957,640). As demonstrated by theanalysis of tetrabutylammonium hexafluorophosphate (FIG. 3B), thepositive ion paper spray-MS method is insensitive to the type of anionassociated with the quaternary ammonium cation. It was also found thatboth short and long chain cations can be analyzed effectively. Table 2provides a summary of data for all the model compounds studied,including their CID fragmentation patterns. Just as in the case of thetetraoctylammonium cation (FIG. 3A), the elimination of both neutralalkene (C_(n)H_(2n)) and alkane (C_(n)H_(2n+2)) was observed during CIDfor all alkyl quaternary ammonium cations studied (Scheme 1 A and B). Itis important to note that the fragmentation pattern was also observedfor the long and short chain model compounds. For example, MS² and MS³spectra for the short chain tetrabutylammonium cations at m/z 242 andm/z 186 via successive eliminations of butene (MW 56) and butane (MW 58)are evident in FIG. 3B insert (v)-(vi).

TABLE 2 Structures and CID product ions of quaternary ammonium compoundsanalyzed in oil MW MS² MS³ Name Structure (cation) TransitionsTransitions Tetraoctyl- ammonium bromide

466.6 466.6→354.5 (loss of C₈H₁₆) 466.6→352.5 (loss of C₈H₁₈)466.6→354.5→242 (Loss of C₈H₁₆) 466.6→352.5→240 (Loss of C₈H₁₈)Tetradodecyl- ammonium bromide

691.0 691→522 (Loss of C₁₂H₂₄) 691→520 (Loss of C₁₂H₂₆) 691→522→354.5(Loss of C₁₂H₂₄) 691→520→352.5 (Loss of C₁₂H₂₆) Tetrahexyl- ammoniumbromide

354.7 354.7→270 (loss of C₆H₁₂) 354.7→268 (loss of C₆H₁₄) 354.7→270→186(C₆H₁₂) 354.7→268→184 (C₆H₁₄) Tetrabutyl- ammonium hexafluoro- phosphate

242.0 242→186 (loss of C₄H₈) 242→184 (loss of C₄H₁₀) 242→186→130 (lossof C₄H₈) 242→186→128 (loss of C₄H₁₀) Hexadecyl- Trimethyl- ammoniumbromide

284.0 Below Scan range Below scan range Benzyl- hexadecyl- dimethyl-ammonium chloride

360.0 360→168 (loss of C₇H₈) Below scan range

Ionization using paper spray-MS was also used to analyze quaternaryammonium corrosion inhibitors in mixtures. Firstly, an artificialmixture was prepared using equal volumes of the quaternary ammoniumcorrosion compounds in acetonitrile/methanol (1:1, v/v) to form amixture of active corrosion inhibitor components. The mixture was thenanalyzed by paper spray-MS under the same conditions as described above:i.e., 10 pg of each compound (in 1 μL of oil) of corrosion inhibitorsolution was spiked onto a paper triangle and analyzed using thecommercial ion trap mass spectrometer, as shown in with a typical massspectrum being shown in FIG. 11. Next a second mixture includingalkyldimethylbenzyl ammonium chloride salts was prepared by mixing equalamounts of the model compounds in pump oil. Analysis of this mixture bypaper spray-MS was again achieved without any sample pretreatment, andthe resulting mass spectrum is shown in FIGS. 4A-B. Both mixtures gaverelatively stable paper spray signals and produced no observable ionfragmentation in the full scan mass spectrum. Relative signalintensities from these mixtures in pump oil corresponded to the amountsin the analyte mixture. Changing the spray solvent from methanol tomethanol/acetonitrile showed no effect on the ion signal intensity ofsignal to noise ratio as described in FIG. 12. Note that this standardsample (alkyldimethylbenzyl ammonium chloride) contains only traceamounts of C₁₆ and this is evident from the relative abundance of thismass spectral signal from this ion compared with that of othercomponents in the mixture (FIG. 12) and in the corresponding total ionchronograms (TIC). In the latter experiment, no m/z 360 (C₁₆) ion signalis observed at 5.5 min, see FIG. 13.

Example 9: Corrosion Inhibitor Analysis Using Portable Ion Trap MassSpectrometer

The success of paper spray-MS in the analysis of quaternary ammoniumsalts from an oil matrix using the bench-top instrument led to analyzingcrude oil with a miniature ion trap instrument (Mini 12.0). Mixtures aswell the individual alkyl and benzyl quaternary ammonium salts wereanalyzed using the Mini 12.0 with paper spray ionization. FIGS. 5A-Bshow data for 1 ng/μL for tetraoctylammonium bromide andbenzylhexadecyldimethylammonium chloride, applied to the paper in 1 μLof pump oil. As was observed, paper spray-MS using the Mini 12.0 gave ahigh ion signal-to-noise ratio even at this low level of analyte. Boththe LTQ and the Mini signals were high enough to allow the identity ofthese compounds to be easily confirmed by tandem MS. Even though theMini 12.0 operates at a relatively high pressure compared with thecommercial instrument, little fragmentation was observed in the fullscan mass spectra. The structural information however, is readilyavailable from MS/MS (FIGS. 5C-D). Again, the tetraoctylammonium cation,m/z 466, fragments on the Mini 12.0 instrument through sequential lossof octene (MW 112) to give ions at m/z 354, 244 and 130. By contrastwith the tetraalkyl salts, the most stable neutral species eliminatedfrom the intact cation, m/z 360, of the trialkylaryl salt,benzylhexadecyldimethylammonium during CID WAS toluene (MW 92) and notan alkene derived from the alkyl groups attached to the quaternarynitrogen. This fragmentation pathway yields a product ion at m/z 268(FIG. 5D). Such a simple fragmentation allowed easy quantification ofvarious aryltrialkyl salts having different alkyl chain lengths in pumpoil (Table 3).

TABLE 3 Structures and Product Ions of CID of the Salt[C₆H₅CH₂N(CH₃)₂R]⁺Cl⁻ Analyzed in Pump Oil by PS-MS using Benchtop andMiniature Instruments Active corrosion MW MS/MS Ion compound (Cation)Transitions Loss Quat C₁₂ 304 m/z 304 → 212 92 Quat C₁₄ 332 m/z 332 →240 92 Quat C₁₆ 360 m/z 360 → 268 92

The paper spray ambient ionization/Mini 12.0 combination was also usedfor mixture analysis. To test this capability, a standard mixture ofalkyldimethylbenzylammonium chloride (i.e., a salt having n-alkylsubstituents C₁₂ (major), C₁₄ and C₁₆) obtained from Sigma Aldrich (St.Louis, Mo.) was dissolved in pump oil. A second mixture consisting offive corrosion inhibitors dissolved in methanol/acetonitrile (1:1, v/v)was prepared in house by mixing equal amounts of tetrabutylammoniumbromide, hexadecytrimethylammonium bromide,benzylhexadecyldimethylammonium chloride, tetraoctylammonium bromide andtetradodecylammonium bromide in pump oil. Typical mass spectra obtainedfor the two different mixtures using the Mini 12.0 are shown in FIGS.6A-B, when 100 pg/μL was examined on paper using the Mini 12.0instrument. For the artificial quaternary ammonium salt mixture, thecomponents in the mixture were observed at m/z 242, 284, 354, 360 and466. For the standard mixture of trialkylarylammonium salts, only twoout of the three mixture components (i.e., C₁₂ and C₁₄) were typicallyobserved in the full scan mode using either the benchtop commercial orthe Mini 12.0 instruments (FIG. 6B) when 1 ng/μL of the mixture wasspiked onto the paper. This is simply because the amount of m/z 360(C₁₆) benzylhexadecyldimethylammonium chloride salt in the mixture wassmaller than that of m/z 332 (C₁₄), which was in turn smaller than m/z304 (C₁₂). The m/z 360 (C₁₆) component could, however, be identified andconfirmed at m/z 360 using the MS/MS experiment as shown in FIG. 3A,insert iii) and FIG. 4B. Structural information was obtained for eachmember of the two mixtures, examples of which are provided in FIGS. 6C-Dusing the Mini 12.0 handheld miniature mass spectrometer.

Direct analysis of corrosion inhibitor active components at very lowconcentrations (<1 ng/μL) in complex oil mixtures has been demonstratedusing paper spray ionization using a portable handheld massspectrometer. The MS/MS experiment provides a powerful means ofqualitative analysis. The resolution of the miniature ion trapinstrument is adequate for these experiments (unit resolution over themass range of interest) and the detection limit is only a factor of ca.10 more than in the commercial bench-top instrument. This detectionlimit is adequate for the direct detection of corrosion inhibitorconcentration levels. Hence the results shown provide evidence that thedescribed techniques can be used for the analysis of corrosion inhibitorconcentrations at levels appropriate to manage the treatment oftransmission pipelines.

1-10. (canceled)
 11. A method for quantifying a corrosion inhibitor incrude oil, the method comprising: obtaining a crude oil samplecomprising a corrosion inhibitor; subjecting the crude oil sample tomass spectrometry analysis; and quantifying the corrosion inhibitor inthe crude oil sample based on results of the mass spectrometry analysis,wherein the method is performed without any sample pre-purificationsteps.
 12. The method accordingly to claim 11, wherein the massspectrometry analysis comprises: introducing the crude oil sample to aporous substrate; applying solvent and voltage to the substrate togenerate ions of an analyte in the crude oil sample; and analyzing theions using a mass spectrometer.
 13. The method according to claim 12,wherein the mass spectrometer is selected from the group consisting of abench-top mass spectrometer and a miniature mass spectrometer.
 14. Themethod according to claim 12, wherein the porous substrate is paper. 15.The method according to claim 14, wherein the paper is filter paper. 16.The method according to claim 11, wherein the corrosion inhibitorcomprises at least one alkyl ammonium salt.
 17. The method according toclaim 16, wherein the alkyl ammonium salt is selected from the groupconsisting of tetradodecylammonium bromide,benzylhexadecyldimethylammonium chloride, and a combination thereof. 18.The method according to claim 12, wherein the mass spectrometer iscoupled with a discontinuous atmospheric pressure interface.
 19. Themethod according to claim 12, wherein the solvent comprises a mixture ofmethanol and acetonitrile.
 20. The method according to claim 11, whereinthe mass spectrometry analysis is performed in an ambient environment.